Synechocystis PCC 6803 transcriptome under glucose and nitrogen stress

Cyanobacteria adapt to nitrogen starvation by undergoing chlorosis, a regulated bleaching response that includes the degradation of photosynthetic pigments and accumulation of carbon storage compounds such as glycogen. While this response is well-characterized under photoautotrophic conditions, how it is modulated by external carbon sources, such as glucose, remains poorly understood.Our objective was to determine how glucose influences the onset of bleaching in Synechocystis sp. PCC 6803 and to uncover the underlying regulatory mechanisms. We found that glucose supplementation prevents the typical bleaching response, even when administered several hours after nitrogen depletion. Interestingly, transcriptomic profiles were largely similar between bleached and non-bleached cells, suggesting that post-transcriptional or metabolic regulatory mechanisms are likely responsible for the observed phenotypic differences.